Multi-position character display panel

ABSTRACT

The display panel is gas-filled and includes a base plate on which a plurality of groups of cathodes and their conductors are formed, each group of cathodes being operable to display a character. The panel also includes a face plate, spaced from the base plate, and carrying transparent conductive anodes, each associated with one group of cathodes. The panel includes a tubulation secured to the base plate through which gas and mercury vapor are introduced into the panel through a hole in the panel base plate. A mass of fibrous material is disposed in the tubulation adjacent to the hole in the base plate to prevent globules of free mercury from entering the panel and, at the same time, permitting mercury vapor to enter the panel.

United States Patent Maloney Mar. 18, 1975 I MULTl-POSITION CHARACTER DISPLAY PANEL lnventor: Thomas C. Maloney, Bernardsville,

Burroughs Corporation, Detroit, Mich.

Filed: Oct. 3, 1972 Appl. No.: 294,535

Assignee:

US. Cl. 313/188, 313/174 Int. Cl. HOlj 61/28 Field of Search 313/220, 210, 188, 177,

References Cited UNITED STATES PATENTS 8/l974 Fehnel 3l3/l77 Primary lirumiwr-Rudolph V. Rolinec Assistant E.\'umincrDarwin R. Hostetter Attorney, Agent, ufFirm-Paul W. Fish; Edward G. Fiorito; Robert A. Green [57] ABSTRACT The display panel is gas-filled and includes a base plate on which a plurality of groups of cathodes and their conductors are formed, each group of cathodes being operable to display a character. The panel also includes a face plate, spaced from the base plate, and carrying transparent conductive anodes, each associated with one group of cathodes. The panel includes a tubulation secured to the base plate through which gas and mercury vapor are introduced into the panel through a hole in the panel base plate. A mass of fl brous material is disposed in the tubulation adjacent to the hole in the base plate to prevent globules of free mercury from entering the panel and, at the same time, permitting mercury vapor to enter the panel.

6 Claims, 4 Drawing Figures EIJEPHEU 1 8195 3,872,339

sum 2 or 2 1 MULTI-POSITION CHARACTER DISPLAY PANEL BACKGROUND OF THE INVENTION It is customary in cathode glow discharge devices, such as the display panel described above, to include mercury vapor in the gas atmosphere to minimize cathode sputtering. Generally, the mercury is introduced from a small glass capsule held in the tubulation which is secured to the panel base plate and communicates with the interior of the panel by way of a small hole in the base plate. The glass capsule containing the mercury is broken at a suitable time in the manufacture of the panel, after the tubulation has been sealed off, to release the mercury and to permit its vapor to enter the panel through the hole in the base plate.

The mercury provided in the glass capsule is a relatively small ball, and, when the capsule is broken, the mercury ball enters the tubulation and some of its vapor flows into the panel through the hole in the base plate. However, a quantity of the mercury ball remains in the tubulation, and, under some circumstances, when the panel or its assembly is physically manipulated, some or all of the mercury ball may enter the panel through the hole in the base plate and may cause shorts between electrodes or may cause other problems.

SUMMARY OF THE INVENTION DESCRIPTION OF THE DRAWINGS FIG. I is a perspective exploded view of a display panel embodying the invention;

FIG. 2 is a sectional view, along the lines 22 in'FlG.

FIG. 3 is a sectional view of a portion of a display panel showing a modification of the invention; and

FIG. 4 is a sectional view of a portion of a display panel showing another modification of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The display panels described herein are thin, flat, sheet-like members which may have substantially any desired size and shape, and may include substantially any number of character display positions. The panels may also include any suitable ionizable gas such as neon, argon, xenon, etc., singly or in combination. A wide range of gas pressure may be used, for example, for about to about 350 Torr or higher at ambient temperature, with about 75 to I20 Torr being a pressure range which is commonly and conveniently used.

Those skilled in the art understand the interplay of parameters which affect the selection of a suitable gas pressure.

LII

The principles of the invention are applicable to many types of cold cathode display devices, and the display panel 10 shown and described herein is a segment-type device which includes an insulating base plate 20 of glass, ceramic, or the likewhich carries, on its top surface, a plurality of narrow conductive leads or runs 30 (A to G).' The runs 30 are'parallel to each other and aligned with the horizontal axis of the base plate. Seven runs 30A to 30G are shown; however, more or fewer may be provided, the number being determined by the total numberand type of characters to be displayed. The runs 30 may be formed by an evaporation process, a silk-screen process, an electroless plating process, are plasma spraying, flame spraying, or the like, or they may be discrete strips of'metal, heatsealed or otherwise secured to the insulating plate 20. A silk-screen printing process is particularly suitable because it is fast, efficient, andreproducible.

A thin layer 40 of insulating material such as glass or ceramic is provided on the conductive runs 30, prefe rably by a silk-screen or spraying process. The layer 40 is provided with a plurality of groups ofapertures 50A to 50G, each aperture exposing one of the runs 30A to 30G. Thus, each group of apertures includes'aperture 50A which exposes run 30A, aperture 50B which exposes run 308, aperture 50C which exposes run 30C, etc.

Panel 10 also includes a group of cathode electrodes 60 (A to G) for each group of apertures 50', the cathodes are generally flat elongated bars or segments, and they are generally arrayed in a figure 8" pattern, as is well known in the art. The cathodes 60may be formed by any of the processes mentioned'above with a silkscreen process or the like performed with a conductive paste such as palladium-gold, platinum-gold, palladium-silver, or the like. Each cathode element fills its aperture 50, is in direct contact with one of the runs 30 exposed thereby, and covers a portion of the top sur- 7 face of layer 40 to achieve the desired shape and size for each cathode.

The cathodes 60 may also be formed of discrete strips ofmetal, each of which is brazed to a conductive run 30 by means of a mass of brazing material deposited in each of the apertures 50in the insulating layer 40. The brazing material may also be deposited by a silk-screen process or the like, with one suitable brazing material being a gold-germanium substance known as FORMONv which is sold by DuPont.

Panel 10 also includes an anode electrode for each group of cathode electrodes 60. The anode electrodes 90 preferably comprise transparent conductive films of gold, NESA, or the like deposited on the lower surface 96 of the panel face plate or viewing plate 100 which is made of glass. The anode films 90 are generally rectangular in shape, or they are otherwise shaped, depending on the orientation of the cathodes, and they are dimensioned and positioned so that they overlay the area defined by each group of cathode electrodes,

as illustrated in FIG. 2. The anode thus face the flat surfaces of the cathodes, and these surfaces generate cathode glow areas of the same general shape in operation of the panel. Alternatively, the anode electrodes may comprise separate screens (not shown) suitably supported above the groups of cathode electrodes.

The top glass cover plate 100 is spaced from the base plate 20 by a rectangular frame member which may beintegral with cover plate 100, or it may be a separate piecewhich is disposed between the top glass plate 100 and the insulating layer 40. The rectangular frame 110 serves to provide the desired spacing between each anode and its associated group of cathode electrodes.

The three glass members 20, 100, and 110 are sealed together by means of an hermetic seal 120 (FIG. 2) formed along the adjacent edges of the members by means of a glass frit or the like.

Suitable contact pins 122 are secured to the cathode runs 30, and contacts 124 are also made to anodes 90, and all contacts are embedded in seal 120.

The panel is filled with the desired gas atmosphere through a tubulation 150 secured to the base plate and communicating with the interior of the panel through a hole 160 in base plate 20.

The tubulation 150 has a flared end 153 which is secured to the surface of the base plate axially aligned with holes 160 and 170. According to the invention, a mass 180 of a fine fibrous material, insulating or metallic, is disposed in tubulation 150 covering hole 160. The material may be in the form of a free irregular mass, or it may be a relatively flat disc or the like as shown in FIG. 3. It may also merely bear against the lower surface of plate 20 covering hole 160, or it may have a portion which enters the hole 160 as shown in FIG. 4. A preferred material for the mass 180 is an insulating material known as Fiberfrax which is made by Carborundum Company.

In addition, as is well known in the art, a mercury capsule 190 is disposed within the tubulation 150 and is held in place in any suitable manner, for example, by means of a constriction in the tubulation. The mercury capsule 190, in one mode of operation, is made of infra-red absorbing glass and contains a small ball of mercury 200.

After panel 10 has been assembled and processed as required, it is filled with the desired gas through tubulation 150, and the tubulation is sealed off at a conveniently short length. Again, at a suitable time in the processing procedure, the glasscapsule is broken,for example, by a suitable heating process, as by the application of infra-red energy to the capsule, and the mercury ball is thus freed from the capsule and deposited in the tubulation. Either mercury vapor from the mercury ball diffuses through the mass 180 and the holes 160 and 170 gradually, or the panel may be heated to forcefully drive mercury vapor into the panel. It is believed that this operation forms a film of mercury 86 on each of the cathodes. Other processing steps are carried out as required to complete the manufacture of the panel 10. The panel is nowready for mounting in a suitable frame or carrier in association with printed circuit boards for ultimate inclusion in an instrument such as a desk top calculator. In these various operations, of course, the panel is handled and disposed in various orientations. It is noted that, during these manipulations, the mass 180 serves to prevent any solid mercury present in the tubulation from entering the panel through the holes and 170. If the mass were not present, mercury droplets might enter the panel and cause shorts between closely spaced electrodes. What is claimed is:

l. A display device comprising a gas-filled panel-like envelope including a base plate and a face plate spaced therefrom, at least one anode and-one cathode electrode within said envelope, a hole in said base plate for permitting gas to leave and enter said envelope, a tubulation secured to said base plate and enclosing said hole, a mass of-mercury in said tubulation, and a mass of fibrous material in said tubulation and positioned to block said hole, said mass permitting the flow of gas and mercury vapor into said envelope through said hole, but preventing the entry of relatively large globules of mercury through said hole into said envelope. 2. The device defined in claim 1 wherein said mass is of an insulating material.

3. The device defined in claim 1 wherein said mass is of metal.

4. The device defined in claim I wherein said mass is in the form of a flat disc.

5. The device defined in claim 1 wherein said mass includes a portion positioned within said hole.

6. A display device comprising a gas-filled envelope including a base plate and a face plate, a plurality of groups of cathode electrodes disposed in said envelope on said base plate, an anode electrode in operative relation with each said group of cathode electrodes, a tubulation secured to said base plate outside said envelope and communicating with the interior of said envelope through a hole in said base plate, said tubulation being adapted for introducing gas and mercury vapor into said panel through said hole in said base plate, and a mass of fibrous material disposed across said hole in said tubulation and adapted to block the passage of foreign material through said hole into said 

1. A display device comprising a gas-filled panel-like envelope including a base plate and a face plate spaced therefrom, at least one anode and one cathode electrode within said envelope, a hole in said base plate for permitting gas to leave and enter said envelope, a tubulation secured to said base plate and enclosing said hole, a mass of mercury in said tubulation, and a mass of fibrous material in said tubulation and positioned to block said hole, said mass permitting the flow of gas and mercury vapor into said envelope through said hole, but preventing the entry of relatively large globules of mercury through said hole into said envelope.
 2. The device defined in claim 1 wherein said mass is of an insulating material.
 3. The device defined in claim 1 wherein said mass is of metal.
 4. The device defined in claim 1 wherein said mass is in the form of a flat disc.
 5. The device defined in claim 1 wherein said mass includes a portion positioned within said hole.
 6. A display device comprising a gas-filled envelope including a base plate and a face plate, a plurality of grOups of cathode electrodes disposed in said envelope on said base plate, an anode electrode in operative relation with each said group of cathode electrodes, a tubulation secured to said base plate outside said envelope and communicating with the interior of said envelope through a hole in said base plate, said tubulation being adapted for introducing gas and mercury vapor into said panel through said hole in said base plate, and a mass of fibrous material disposed across said hole in said tubulation and adapted to block the passage of foreign material through said hole into said panel. 